The invention is generally related to termite bait stations for monitoring and controlling subterranean termites and the associated method.
It has long been known that termites can enter homes and other man-made building structures and cause serious damage. Moreover, it has been reported that termites, and especially subterranean termites, cause more damage to the wooden portions of building structures than any other insect. Preventing termite damage to building structures is critical to avoiding related expensive repairs and unsafe conditions.
Preventing termites from finding and colonizing in the wooden portions of building structures is often achieved by keeping water away from the wooden portions. Subterranean termites need moist living conditions to survive. The absence of water near the source of food for termites makes the wooden portions unattractive for colonizing.
Another benefit for keeping water away from the wooden portions is preventing subterranean termites from being lured by water-soluble components that attract termites. Water extracts water-soluble compounds from the wood. In addition, water encourages decomposition of the wood by fungi growth that also causes water-soluble compounds. If the wooden portions of the building structure are kept dry, the subterranean termites may then not find them.
Unfortunately, it is not always possible to prevent water from intruding into wooden portions of building structures. Factors such as climate, design of the building structure, state of repair, proximity of natural water sources, etc., create a possibility that at some point subterranean termites will find the wooden portions of the building structure.
Before the environmental and human impacts were appreciated, it was the practice to prevent wood-destroying insects from significantly damaging a building by adding persistent chlordane termiticides to the building and to the soil around the building. Such termiticides killed subterranean termites near or in the building for significant periods of time.
After these persistent termiticides were banned, the options available to prevent termite damage required a more frequent method for monitoring and responding to termite infestations. For example, available termiticides have a shorter period of effectiveness, and thus have to be repeatedly reapplied. Reapplication may be difficult or inappropriate since many wooden portions of a building are no longer readily accessible for treatment after the building is finished. Avoiding reapplication is often desired to reduce the cost, especially when no termite activity has been detected. Even if reapplied, termite infestation at or near the treated area is possible depending on how the treatment was performed and the environment affecting the treated area.
The disadvantages of only treating the building structure has led to use of bait stations for controlling termite activity by monitoring and/or killing termites. Typically, termite bait material such as piece of wood is placed within a container that is buried near a building. Water is allowed to enter the bait station and to extract water-soluble compounds from the wood. The water with the extracted compounds drains away from the bait station, luring subterranean termites to the bait station. The bait station also allows termites to enter therein. Different techniques are used to control termite activity in response to termites being lured into the bait station and detected.
Some bait stations require periodic visual inspection of the bait material for termite damage. Consequently, an elaborate means must be provided for removing the bait material from the station or for removing the entire bait station from the ground.
It is also generally known to use termiticide-impregnated wood as the bait material. Thus, the bait material not only lures the termites but also kills those that are lured into the bait station. This technique requires a significant economic expense of replacing termiticide lost into the soil or lost through decomposition due to exposure. However, it is also undesirable to unnecessarily dispense toxicants of any sort into the environment due to possible collateral damage to other plants and animals. Additionally, it is further possible that immunity will develop in the target populations after exposure to nonlethal doses.
Furthermore, use of termiticide-impregnated bait material may fail in the ultimate goal of protecting the adjacent building. Subterranean termites are random, opportunistic foragers that may find the adjacent building rather than a nearby bait station. Increasing the attractiveness of the bait station may be detrimental to protecting the building if the bait station then attracts termites from a larger radius than otherwise would. With this limitation in attractiveness, the bait station may be killing those termites that are lured into the bait station while other termites continue to damage the nearby building. No monitoring function is performed to alert a user that additional steps should be taken to protect the building structure with known systems.
Other techniques for controlling termite activity with a bait station do focus on monitoring termites at a bait station rather than merely killing termites. For instance, detection based on elevated methane gas levels produced by termites when digesting cellulose from wood materials is generally known. In one known system, a plurality of holes in an active bait station allow termites to enter. Termite activity changes the atmosphere within the active bait station and the atmospheric changes are registered by a permanently installed sensor. A computer system, wired to the active bait station, monitors the sensor, as well as sensors in other active bait stations and at least one control bait station. The control bait station is exposed to the same environment but is constructed so that termites cannot enter. Sensor readings significantly higher than the control station are deemed indicative of termite activity.
Once readings are at a level that indicates a termite colony, termiticides may be employed that use a slow-acting toxicant that tends to be shared amongst the termites, killing the entire the colony. Other termiticides use an insect growth regulator to disproportionately produce soldiers over workers to starve the colony. Consequently, the monitoring of termite activity results in a more effective solution, preventing the spread of termites by luring and killing an entire termite colony rather than just individual foraging termites.
While monitoring methane gas is effective in detecting the presence of termites, generally-known methane monitoring bait stations have a number of problems. The cost of each bait station is impacted by requiring a sensor for each station. The perimeter around a building may be large, requiring a large number of bait stations, and a corresponding large number of sensors. Moreover, the sensors are exposed to a humid environment within each bait station, degrading the reliability of the sensors. In addition, a complex system of wiring and data processing is necessary for monitoring the large number of sensors. Also, with the sensors and the interconnections between the sensors and the data processing subject to damage, monitoring may be subject to false alarms or failure to provide an alarm when warranted.
Consequently, a significant need exists for a more reliable, cost efficient, and effective subterranean termite monitoring device and method.
The invention addresses these and other problems associated with the prior art by providing an apparatus and method of monitoring termite activity near a building structure. In one particular embodiment of this invention, an environmentally safe bait material is used to lure subterranean termites to a bait station. Detecting methane gas produced by termites yields an effective and timely indication that use of a termiticide or other control measure is warranted. Due to the slow rate at which termites cause damage, a periodically used methane detector allows for a more reliable and economical way of monitoring subterranean termites.
In one embodiment of the invention, a bait station is in the form of a permeable container that is configured to hold bait material. Termites are able to access the bait material when the permeable container is buried. A container monitoring portion, in gaseous communication with the permeable container, is partially exposed above ground when the permeable container is buried. An access port is selectively closed to inhibit the escape of gases contained in the container through the access port. Consequently, methane gas accumulates if termites are present in the bait station and can be detected by a methane detector which is periodically inserted through the access port. Reliability of the methane detector is thus enhanced by limiting its exposure to the elements.
In another aspect consistent with the invention, a system for detecting subterranean termites proximate to a building structure uses a plurality of the bait stations substantially buried around a perimeter, increasing the likelihood that a foraging subterranean termite will encounter a bait station rather than the building structure. Each bait station is individually and periodically checked for methane gas levels with a methane gas detector, providing further economic savings by having one sensor for the plurality of bait stations. Moreover, a single methane gas detector may be used at other locations and with a plurality of bait stations, thereby yielding additional cost savings. Also, the system does not require wiring or other physical connection between the bait stations that would be damaged by gardening or trenching near the bait stations.
These and other advantages and features, which characterize the invention, are set forth in the claims annexed hereto and forming a further part hereof. However, for a better understanding of the invention, and of the advantages and objectives attained through its use, reference should be made to the Drawings, and to the accompanying descriptive matter, in which there is described exemplary embodiments of the invention.